Beam scanning in the Cassegrain antenna system by the use of subreflector movement

It is noted that the ability to beam scan by suboptic motion is particularly useful in large space antenna systems where main reflector motion would disturb the mission platform. With the use of an offset Cassegrain configuration, the main beam can be scanned by moving only the subreflector. This method of beam scanning results in a reduction of moving mass of more than an order of magnitude. The optimal scan path for the subreflector can be determined through a geometrical optics optimization of subreflector position to minimize aperture plane phase error for each desired angle of scan. The scan path optimization method was tested by optimizing an offset Cassegrain antenna system. The optimized system was tested by computing far-field patterns using the TICRA GRASP7 electromagnetics package at 10 GHz.<>